Anatomy Skeletal System Textbook

composed of bones, cartilages, and ligaments joined tightly to form a strong, flexible framework for the body

Skeletal system

joint surfaces in the mature skeleton

Cartilage location

A cord or band of tough collagenous tissue binding one organ to another, especially one bone to another

ligaments

soft bloody or fatty material enclosed in the bones

bone marrow

support
protection
movement
blood formation
storage

functions of skeletal system

limbs and vertebral column support the body
mandible and maxilla support the teeth

Support function

bones enclose and protect the brain, spinal cord, lungs, heart, and pelvic viscera

Protection Function

movements of the limbs, and other movements such as breathing, are produced by the action of muscles on bones

Movement Function

Red Bone marrow is the major producer of blood cells

Blood Formation Function

skeleton stores calcium and phosphorus
fatty bone marrow has fuel

Storage Function

affects blood sugar regulation, fertility, and brain function in mammals

other functions of the skeleton

osseous tissue, a connective tissue with a hard, calcified matrix

bone

compact (dense) bone
spongy bone

2 forms of bone

consists of a solid matrix

compact (dense) bone

porous lattice honeycombed with spaces

spongy bone

interior of bone

where is spongy bone found

osseous tissue
organ (femur)

2 meanings for bone

osteogenic
osteoblasts
osteocytes
osteoclasts

Four kinds of bone cells

bone surface, beneath the fibrous connective tissue membrane that covers a bone

osteogenic cells location

give rise to osteoblasts
only bone cells that divide and make more bone cells

osteogenic cells function

lie in a single layer on the bone surface, somewhat resembling a cuboidal epithelium

osteoblasts location

bone-forming cells that synthesize the organic matter of the bone and promote its mineralization

osteoblasts function

reside in cavities called lacunae, which are connected to each other by channels called canaliculi

Osteocyte locations

pass nutrients and chemical signals
pass metabolic wastes
orchestrate bone remodeling
maintenance of bone density
sense mechanical stress
secrete signals that adjust bone shape and density

Osteocyte function

90%

how much of bone cells are osteocytes

osteoblasts become trapped in the matrix the deposit

how are osteocytes made

lie one the bone surface
lie in pits that they have eroded

osteoclasts location

bone-dissolving cells that develop from a separate line of bone marrow stem cells

osteoclasts function

stony matter that surrounds the osteocytes and lacunae

matrix of osseous tissue

bones being soft and bending easily

deficient in minerals can cause

childhood mineral deficiency

rickets

adulthood mineral deficiency

osteomalacia

flexibility

collagen gives bones

consists of porous lattice of slender rods and plates called trabeculae

spongy (cancellous) bone

bone marrow and small blood vessels

spaces of spongy tissue are filled with

forms the hard outer shell of the bone. Prevents bone marrow from seeping out and provides a solid attachment surfaces for muscles, tendons, and ligaments

compact (dense) bone

A structural unit of compact bone consisting of a central canal surrounded by concentric cylindrical layers of matrix

osteons

A little plate or layer in compact bone that arranges around a central canal

lamellae

long bones

what are the most important bone for movement

The shaft of a long bone (elongated midsection)

diaphysis

The head of a long bone (expanded end)

epiphysis

provides leverage

shaft function

strengthen a joint and provide added surface area to for the attachment of tendons and ligaments

head function

A thin layer of hyaline cartilage covering the articular surface of a bone at a synovial joint

articular cartilage

serving to reduce friction and ease joint movement

articular cartilage function

spongy bone

what is the head and shaft filled with

marrow (medullary) cavity of the shaft and spaces between the spongy bone

where is bone marrow occupying

the line marking the site of an epiphyseal plate that has has stopped growing and become ossified.

epiphyseal line

shieldlike plates that protect delicate organs

flat bones

sternum- heart
cranial bones- brain

organs flat bones protect

bones that don't fit the description of flat and long bones

short and irregular bones

A layer of fibrous connective tissue covering the surface of a bone.

periosteum

provides strong attachment and continuity from muscle to tendon to bone

periosteum function

a thin layer of reticular connective tissue separating the bone from the bone marrow (internal surface)

endosteum

red bone marrow
yellow bone marrow

2 types of bone marrow

serves to produce blood cells and platelets, fills nearly every bone of a child's skeleton, but is more distribution in adults

red bone marrow

fatty bone marrow that dominates the long limb bones of adults

yellow bone marrow

formation of bone

ossification

intramembranous
endochondral

2 types of ossificaiton

A process in which a sheet of mesenchyme becomes calcified to form a bone, employed primarily for the production of flat bones such as those of the cranium.

intramembranous ossification

fontanels

another name for gaps

A process in which a hyaline cartilage precursor (model) is replaced by calcified tissue to form a bone; employed for the production of most bones of the body except for flat bones of the skull and part of the clavicle.

endochondral ossification

hyaline cartilage covered with pericondrium

Step 1 of Endochondral Ossification

in a primary ossification center chondrocytes enlarge and die. Thin walls calcify. Osteoblasts deposit thin layer of bone around model, forming a collar

Step 2 of Endochondral Ossification

blood vessels pierce the periosteum at the primary ossification center. Osteoclasts digest calcified tissues, hollowing out the shaft and creating the primary marrow cavity. Osteoblasts deposit layers of bone, thickening shaft. Secondary ossification center develops

Step 3 of Endochondral Ossification

secondary ossification center has hollowed out secondary marrow cavity. Another ossification center appears

Step 4 of Endochondral Ossification

epiphyseal plates separates marrow cavities. Plate is a growth zone

Step 5 of Endochondral Ossification

cartilage in epiphyseal plate is depleted
marrow cavities unite into single medullary cavity
bones can no longer grow

Final step of endochondral ossification

accommodate changing forces applies to the skeleton
addition of new tissue to the bone surface

why do bone change size and shape

stimulates an increase in bone mass

what does tension do to the skeleton

maintenance
growth
remodeling
exchange minerals with extracellular fluid

bones functions as an metabolically active organ

calcium and phosphate

skeleton is the body's primary reservoir for

bone structure
component of DNA, RNA, ATP, phospholipids, and other compounds

phosphate function

bone structure
muscle contraction, blood clotting, exocytosis, nervous communication, and cellular responses to hormones

calcium function

crystallization process in which osteoblasts extract calcium, phosphate, and other ions from the blood and deposit them in the osseous tissue

mineral deposition

process in which the osteoclasts dissolve bone, releasing minerals into the blood and making them available for other uses

resorption

A deficiency of calcium ions in the blood that causes dysfunctions ranging from muscle tremor to tetanus (inability of the muscle to relax)

hypocalcemia

An excess of calcium ions in the blood that depresses nervous, muscular, and cardiac function

Hypercalcemia

calcitriol
parathyroid hormone

what 2 hormones regulates calcium homeostasis

most active form of vitamin D
promotes calcium absorption in the small intestine
reduces urinary loss of calcium
stimulates osteoclasts to release calcium from the bones

calcitriol

rickets

low levels of calcitriol result in

secreted by the parathyroid glands
stimulates bone resorption by osteoclasts
promotes calcium reabsorption by kidneys
promotes calcitriol synthesis

parathyroid hormone (PTH)

fracture results from an unusual stress on a bone

stress fracture

bone has been weakened by some other condition, and it fractures under a stress that a healthy bone would withstand

pathological fracture

any fracture that breaks through the skin

open fracture

fracture does not break through skin

closed fracture

descriptions of bones that include a variety of ridges, spines, bumps, depressions, holes, and joint surfaces

bone markings

a tubular passage or tunnel in a bone

Canal Bone marking

a rounded knob

condyle Bone marking

a narrow ridge

crest Bone marking

a flare superior to a condyle

epicondyle Bone marking

a smooth joint surface that is flat or only slightly concave or convex

facet Bone marking

a slit through a bone

fissure Bone marking

a hole through a bone, usually round

foramen Bone marking

a shallow, broad, or elongated basin

fossa Bone marking

a cavity within a bone

sinus Bone marking

any bony prominence

process

a sharp, slender, or narrow process

spine Bone marking

a small, rounded process

tubercle Bone marking

a rough surface

tuberosity Bone marking